Clutch and brake control on road vehicles



Jan. 9, E923.

` J. G. P. THOMAS.

CLUTCH AND BRAKE CONTROL 0N ROAD VEHICLES.

F|LED OcT.

ramas am., a i923;

JOHN GODFB/EY PARRY THOMASOF PRESTON, EII'GCLAND.

cLU'rcn AND BRAKE ooivffrRoL` on ROAD vRHrcrins pplication'led 0ctober19, 1920, Serial Ifo-417,859.

To all whom '13# may concern.' Be it known that I, JOHNl GODFREY PARRY THOMAS, a. subject of the King -of Great Britain and Ireland, residing at 5 Lathom Street, Preston, Lancashire, Englandhave invented new and useful Clutches and Brake Controls on Road Vehicles, of which the following is a specification.

This invention relates to the operation and control of -the brakes and clutches of motor road vehicles. IIt consists in an apparatus which enables the brake to be .applied or the clutch to be engaged by power, the extent of application or engagement being controlled by a pedal or handle of usual form; while in the event of the failureof the power the pedal or handle serves for the application of the brake or -clutch by foot or hand the usual manner.

The invention is hereinaftei1 described in its application to a pedal controlled brake; the substitution of a handle for the pedal, or the application of the invention to a clutch instead of to a brake, will need no separate explanation, the word pedal7 be ing read as including handle and brake as including clutch.

ln'order that the degree of application of the brake-may be controlled by the pedal the power i-s arranged to be applied upon depression of the pedal, and to be cut 0R upon the consequent movement of the brake occurring; or in other words the admission of power is dependent on relative or non-corresponding movement of the pedal and brake," that is to say, upon movement of one member which is not accompanied by corresponding movement of the other.

vA convenient source of power for the purpose is the suction pipe of the internal combustion engine by whichy the road vehicle is propelled, for -even when the engine i-s only turning over light a vacuum of eight to ten pounds is available in this pipe. In a preferred construction a power cylinderl operated from this source is arranged with its axis in the line of movement of the pedal, which is guided upon the piston'rod and can be depressed relatively to itagainst the action of a spring. Any such depression perl mits the opening of a valve under spring or fluid pressure, bv which the interior of'the cyllnder isconnected with the suction pipa; and a sufficient depression of the pedal relative to the piston rod closes a valve `or port through which the interior of the cylinder is open to the atmosphere. The piston rod'is interconnected with the brake lever sothat its movement, whether under the pressure on the piston or the pressure on the pedal, w1ll cause the application of the brake.

Further details of this preferred construction may be seenfrom the accompanying drawing which shows it diagrammatically in longitudinal section.

In this figure 1 is the pedal, the stern 2 of which slides within the end of the hollow piston rod 3 against the action of a spring 4: interposed between the stem 2 and a shoulder in the piston rod. The power cylinder is indicated at 5 and its piston at 6. The brake lever -7 has a forked end in position to be engaged by a collar 8 secured upon 4the piston rod which is guided in a gland 9 and bracket 10 or in other suitable fashion.

It will be apparent that the brake lever 7 will be operated upon movement ofthe piston rod 3, whether such movement results merely from depression of the pedal after the spring 4 is compressed, or from movement ofthe piston 6.- s usual the brake lever is lifted or the brake pressed into odposition by a suitable spring, not shown.

There is attached to the stem 2 of the pedal a tubular prolongation 11 which eX- tends completely through the piston rod and piston, and at its end beyond the piston carries a screw cap 12 which attaches to it the enlarged head 13 of a rod'll. This head is small enough to pass freely into the tube 11, so that it is not of necessity pushed down when the pedal is depressed, but is positively pulled up when the cap 12 engages it. ln the stem 2 there is formed a port 15, and this ported stem, co-operating with the hollow piston rod 3, constitutes a valve which .is closed by a suiicient depression of thev pedal 1 relatively to the piston rod. Through this port 15 and through a similar port 16 in the tube 11 and throughthe tube itself the interior of thev cylinder 5 is normally connected with the atmosphere.

The rod 14 is attached to and operates a piston valve consisting of a lpiston 1T Inoving in a small cylinder 18,. This piston may normally be pressed downward by a spring; but in the construction shown the lower end of the cylinder isv permanently connected with the suction pipe of the engine through a pipe 19,` so that the suction continually' exerted on the piston 1.7. sutlices to pull it down when the cap 12 permits. Then sufliciently lowered the piston 17 uncovers a port 2() connected through pipe 21 with the suction pipe of the engine.

The operation of the apparatus is as follows: Initial pressure upon the pedal 1 moves it downward relatively to' the piston 3, compressing the spring el, that spring being weaker than the spring which holds the brake off. Such movement permitsthe piston 17 to move downwards and to uncover the port E20. The interior of cylinder 5 is then connected with the suction pipe ofV the engine, but' as it is still also connected with the atmosphere through the port 15, air i is at first idly drawn through that port and the tube 11, and the brake is not operated. But when the pedal 1 has been sutliciently depressed to bring the port 15 wholly within the piston rod 3, and thereby close it, thc suction exerted on the piston 6 pulls it down and through the collar 8 and lever 'l'v applies the brake. It the pedal 1 is not further depressed the movement of the piston rod 3 will uncover the port 15, whereupon such movement will stop. If the pedal` 1 is further depressed the `brake lever 7 must move further before the port 15 can again be uncovered. Thus the extent of depression of the pedal governs the extent of application of the brake.

Nevertheless, if for any reason, as through the engine stopping, power should fail, the depression of the pedal will obviously, after the spring 4 is compressed, itself cause movement of the" piston rod and therefore of the brake lever 7 under the pressure of the foot. lVhat I claim is M 1. In a motor roadvehicle having an internal combustion engine the combination with a control` lever, of a cylinder 'and piston adapted to operate said lever, a control device operable by the driver, a connection between said cylinder and thel suction pipe of the engine,l and a valve connecting said cylinder with the atmosphere depending on the positions of both said lever. and said control device.

2. In a motor road vehicle having an in ternal combustion engine, the combination of a control lever with a cylinder and piston adapted to operate said lever, a control device operable by the driver, a valve connecting said cylinder with the suction pipe of the engine. a connection between said mounted on and slidable along said piston.

rod to a limited extent, a spring resisting y.

movement of said pedal along said rod, and means admitting power to. said cylinder adapted'to be actuated by` said pedal.

4;. In a motor roadvehicle, the combination of a control lever, a control device actuated by the driver, a yielding connection lbetween said device and said lever permitting limited movement of said device without movement of said lever, and a power ap- 'paratus for actuating said lever `governed by motion of said control device which strains said yielding connection.

5. In a motor road vehicle having an internal combustion engine, the combination with a control lever, of a power cylinder op-v erating said lever, a valve connecting said c vlinder with the suction pipe of the engine, and a control device actuated by the driver for governing said valve.

6. In a motor road vehicle having an internal combustion engine, a power unit for actuating control apparatus, comprising a cylinder and piston, a valve connecting said cylinder with the suction pipe of the internal combustion engine, a second valve connecting said cylinder with the atmosphere, and a control device operable by the driver Jfor opening the first valve and closing the second.

7. In a motor road vehicle having an internal combustion engine, the combination with a control lever, of a cylinder and piston adapted to operate said lever, a control device operable by the driver, a yielding connection between said device and said lever, permitting the lever to be operated by said device after limited independent movement of the device, a valve connecting said cylinder with the suction pipe of the engine, and a second valve closed by movement of the control device not accompanied by movement ot' the lever connecting said cylinder with the atmosphere.

8. In a inotor road vehicle having an internal c1 nbustion engine, the combination of a control lever with a cylinder, piston and hollow piston rod adapted to operate said'lever, a control pedal operableby the driver mounted on and slidable along said piston rod and forming therewith a valve connecting said cylinder with the atmos` pliere, and means connecting said cylinder laov 9. In a motor road vehicle the combinaing said lever, and means admitting power tion with a control lever, of a control device to said apparatus depending on the position for actuation by the driver, a yielding conof both said lever andfsaid control device. 10

' necton between said device and said lever In Witness whereofl have hereunto signed 5 permitting the lever to be operated by said my name this 4th day of October, 1920.

device after limited independent lmovement of the de-vice, a power apparatus for actuat- J. G. P. THOMAS. 

